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Is Soy Healthy or Not?

Soy is one of those foods that tends to be both vilified and glorified. One day it's good for you, the next it's bad, depending on who you listen to. So, here's the real scoop.
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Hi, I'm Maria Marlowe, a Certified Health Coach and author of Detox without the Deprivation. In my weekly "Ask Health Coach Maria" series, I answer frequently asked questions related to health and wellness. Have a question? Ask me, here.

Hi Maria,

I see soy everywhere, but I hear so much conflicting information about it that I'm not sure it's a healthy choice. Should I go soy-free?

Erin M.

Soy is one of those foods that tends to be both vilified and glorified. One day it's good for you, the next it's bad, depending on who you listen to.

So, here's the real scoop.

A lot of the soy confusion centers around cancer. Does soy prevent cancer or promote it? Much of the controversy comes from the fact that soy contains phytoestrogens (plant estrogens, which mimic the female hormone in humans), which is wrongly believed to promote estrogen-related cancers like breast cancer and endometrial cancer. In numerous human epidemiological studies, which follow women over many years, results have consistently shown that soy either has no effect on breast cancer risk, or may even slightly lower it. And for breast cancer survivors, one study found that increased soy intake reduced risk of recurrence.

Soy is safe for men, and studies show it will not alter their testosterone levels.

Another concern about soy is the idea that it promotes hypothyroidism. This one is a little less clear-cut. While clinical studies show that soy does not cause hypothyroidism, soy isoflavones may take up some of the iodine that the body would normally use to make thyroid hormone. So that means that people who eat soy must make sure to consume adequate iodine, which can be found in salt, fish, and vegetables, particularly sea vegetables.

On the nutrition front, besides being an excellent source of plant protein, soy is high in fiber, antioxidants, omega-3s, and vitamins and minerals, including iron and vitamin K.

So, there is no need to fear soy... as long as you are consuming the correct variety.

Not all soy is created equal. Fermented soy is the best choice, and processed soy should be avoided. Soy is not a necessary component of a healthy diet, but, if you do choose to include it, stick to fermented and organic varieties.

Fermented Soy

While soy contains many nutrients, it also contains anti-nutrients, which inhibit nutrient absorption. However, when soy is fermented, these anti-nutrients are reduced, and soy's healthful properties become more available and digestible. Fermented soy has been a staple of Asian diets for thousands of years.

Different types of fermented soy include tempeh, miso, natto, and soy sauce. Again, note that conventional soy tends to be genetically modified, so choose organic to avoid GMOs.

Unprocessed Soy

Unprocessed soy (edamame) is hard to digest and still contains anti-nutrients. So consume sparingly, if at all, and of course, choose organic.

Processed Soy

Processed soy, which typically shows up on ingredient lists as soy protein isolate, textured vegetable protein, or soy isoflavones, is essentially just the protein and phytoestrogens of the soy, without all the antioxidants, vitamins, and other nutrients found in their whole form. This type of soy is usually found in highly processed and "junk" foods, which you want to avoid anyway. Tofu is also a type of processed soy. Since there is not much research solely on isolated soy products, and they are found in highly processed foods, I generally advise my clients to avoid them.

Additionally, note that soy, like peanuts, is a common allergen. Of course, if you do have a soy allergy, then it is best to avoid.

For fermented soy lovers out there, do you have any recipes you can share with us? Tell us in the comments below!

Maria Marlowe is a Certified Health Coach and regular Wellness Today Contributor. Get your health question answered in her next column by sending her an email at

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